| Chemical Abstract Number (CAS #) |
75058
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| Synonyms | Acetonitrile |
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Methyl cyanide | Ethanenitrile |
| Analytical Methods |
EPA Method 8240B |
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EPA Method 8260A |
| Molecular Formula | C2H3N |
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| Use | In organic synthesis as starting material for acetophenone, alpha-naphthaleneacetic acid,
thiamine, acetamidine. To remove tars, phenols, & coloring matter from petroleum hydrocarbons
which are not soluble in acetonitrile. To extract fatty acids from fish liver oils & other animals &
vegetable oils. Can be used to recrystallize steroids. As an indifferent medium in physicochemical
investigations. Wherever a polar solvent having a rather high dielectric constant is required. As
medium for promoting reactions involving ionization. As a solvent in non-aqueous titrations. As a
nonaqueous solvent for inorganic salts.
Acrylic fibers; pharmaceuticals; perfumes; nitrile rubber; ABS resins
Acetonitrile is used as a chemical intermediate in pesticide manufacture.
Solvent for both inorganic and organic compounds, including polymers. Starting material for
many types of nitrogen-containing compounds, eg, amides, amines, higher molecular weight
mono- and dinitriles; halogenated nitriles; ketones; isocyanates; and heterocycles, eg, pyridines
and imidazolines
A variety of lithium salts when dissolved in anhydrous organic solvents, eg, acetonitrile from
electrolyte compositions for nonaqueous batteries.
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| Apparent Color | COLORLESS, LIMPID LIQUID
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| Odor | AROMATIC ODOR ; ETHER-LIKE ODOR
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| Boiling Point | 81.6 DEG C AT 760 MM HG
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| Melting Point | -45 DEG C
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| Molecular Weight | 41.05
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| Density | SP GR: 0.78745 @ 15 DEG C/4 DEG C
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| Odor Threshold Concentration | Low: 70.0 mg/cu m; High: 70.0 mg/cu m; Irritating: 875 mg/cu m
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| Sensitivity Data | Immediately irritating to the eye.
May cause skin irritation.
Vapor: irritating to eyes, nose and throat. Liquid: irritating to skin and eyes.
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| Environmental Impact | Acetonitrile is released to the environment during its manufacture and use, from shale oil
retorting and coal gasification, incineration of polyacrylonitrile, from automobile exhaust and
cigarette smoke. If released to soil, aerobic biodegradation is likely to occur. Acetonitrile is
expected to be mobile in soil and may evaporate from soil surfaces. Biodegradation is expected to
be a major loss process in water. Acclimatization increases the biodegradation rate substantially.
Volatilization may become competitive with other loss processes particularly at shallow water
depths. Hydrolysis, photolysis, adsorption to suspended particles and sediments and
bioconcentration in aquatic organisms are not likely to be important fate mechanisms. Acetonitrile
is likely to be unreactive towards direct photolysis in air and the half-lives for its reaction with OH
radicals and ozone have been estimated to be 535 days and 860 days, respectively. Therefore, it
will persist in the troposphere for a long time and may be transported a long distance from its
source of emission. Wet deposition may remove some of the atmospheric acetonitrile. Adequate
data regarding its typical concentrations in air, water and total diet sample are not available to
estimate intake from these exposure routes.
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| Environmental Fate | TERRESTRIAL FATE: Although no conclusive study demonstrating the biodegradability
of acetonitrile in grab soil samples is available, it can be inferred from the pure culture and
biodegradability studies in water that the compound may biodegrade in soil. Photolysis
studies in air(3,4) and hydrolysis studies in water suggest that acetonitrile would not undergo
appreciable photolysis or hydrolysis in soil. Based on an estimated Koc value of 16(1,6),
acetonitrile would be weakly sorbed to most soils. The high water solubility, moderately high
vapor pressure , and weak soil sorption of the compound suggest that volatilization from soil
surfaces and leaching into groundwater would be important.
AQUATIC FATE: A number of biodegradation studies with sewage, activated sludge, and pure
cultures serving as microbial organisms have shown that acetonitrile is biodegradable in water
following acclimatization, as long as its original concentration is not too high (eg, 500 mg/l). The
decomposition of the compound (concn 0.1 to 25 mg/l) in Ohio River water was 20% in 5 days
and 40% in 12 days . Biodegradation was faster in water following acclimatization.
Photochemical studies in the vapor phase(5,6) suggest that photodegradation in water may not be
important. Hydrolysis is unimportant at the pH range normally present in natural waters . Based
on the value of 2.93X10-5 atm cu m/mole for Henry's Law constant (H) and the relationship
between H and volatility(6), volatilization of the compound from water may not be rapid, but may
become competitive with other loss processes particularly at shallow water depths. The high
water solubility and low Koc of acetonitrile would suggest that adsorption of the compound to
suspended solids and sediment in water and bioconcentration in aquatic organisms would be
unimportant.
ATMOSPHERIC FATE: The rate constant for the reaction of acetonitrile with OH radicals in air
has been determined to range from 1.9X10-14 to 4.94X10-14 cu cm/molecule-sec in the
temperature range 20 to 27 deg C(1-5). Based on a rate constant of 3X10-14 cu cm/molecule-sec
and the average daily OH radicals concn of 5X10 5 radicals/cu cm in the atmosphere , the
half-life of this reaction is 535 days. The rate constant for the reaction of acetonitrile in air with
ozone is 1.3X10-20 cu cm/molecule-sec(6). In a typical atmosphere where the average daily
ozone concn is 7.2X10 11 molecules/cu cm , the half-life due to this reaction would be 860
days. The photochemical smog studies also show that this compound is unreactive towards
photochemically-generated free radicals(8). Acetonitrile is also unreactive towards direct
photolysis in the gas phase(7,9).
EFFL: Acetonitrile was qualitatively detected in shale oil wastewaters and wastewater from
coal gasification process(2,3).
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